From Byproduct to Breakthrough: Agronomic, Environmental, and Regulatory Aspects of Phosphogypsum Use in Agriculture

Phosphogypsum (PG), a calcium sulfate-rich byproduct of phosphate fertilizer production, is generated in vast quantities worldwide and represents a major environmental management challenge. At the same time, its chemical composition makes PG a potentially valuable soil amendment, particularly for the reclamation of saline, sodic, and acidic soils. This review critically synthesizes current knowledge on PG generation processes, physicochemical properties, agronomic performance, and associated environmental and health risks. Evidence from peer-reviewed studies demonstrates that appropriately managed PG applications can improve soil structure, enhance water infiltration, reduce sodium toxicity, alleviate aluminum stress, and increase crop productivity. However, PG contains variable levels of impurities, including heavy metals and naturally occurring radionuclides, which raise concerns regarding soil contamination, groundwater pollution, food safety, and human health, especially under high or repeated application rates. Regulatory frameworks governing PG use differ substantially between regions, reflecting inconsistencies in waste classification, radiological thresholds, and leaching criteria. This review highlights key knowledge gaps related to contaminant mobility, bioavailability, and long-term ecological impacts and discusses mitigation strategies such as purification, controlled application rates, and integrated regulatory oversight. By balancing agronomic benefits against environmental risks, this work provides a comprehensive framework for the safe valorization of phosphogypsum in agriculture, supporting sustainable land management and circular economy objectives.